Sanitary napkins



y 7, 1953 c. HARMON 3,088,464

SANITARY NAPKINS Filed June 3, 1960 INVENTOR f/P2 r4: h/P/va v i mrw ATTORNEY United States Patent 3,088,464 SANITARY NAPKINS Carlyle Harmon, Scotch Plains, N.J., assignor, by mesne assignments, to Johnson 8: Johnson, New Brunswick, N.J., a corporation of New Jersey Filed June 3, 1960, Ser. No. 33,783 Claims. (61. 1282.9ti)

The present invention relates to absorbent dressings, particularly those of the sanitary napkin type, and is directed to improving the sterilizable and non-blocking properties thereof.

Sanitary napkins customarily have a relatively thick, flexible, absorbent pad or core wrapped within a relatively thin, pervious cover or sheath which serves the two-fold purpose of holding the absorbent core together and providing supporting or pinning tabs at the ends thereof whereby the sanitary napkin can be secured to a belt. The most generally used fabricated material for the cover or sheath has been a woven gauze, although scrim has often been used. Scrim is a fabricated material in which the strands are merely laid across each other at 90, or at any desired acute angle, in a laminated layer construction without any positive interweaving or interengaging of the individual strands.

Such gauze and scrim cover fabrics, being very loosely interwoven or overlaid, are usually lightly bonded by an adhesive to prevent undesirable lateral movement, slippage or separation of the individual strands. When an adhesive bonding agent is used, such has normally been polyacrylic resins, polyvinyl acetate, polyvinyl chloride, or other vinyl resins.

When these sanitary napkins are sold at the consumer or retail level, the properties of softness, strength, comfort and absorptive capacity are most important and are usually determinative of the commercial success of the product. However, when these sanitary napkins are sold to the hospital trade, such as for use in maternity wards for post-natal care, an added requirement of sterilizability is introduced in order to lessen the possibility of infection, contamination, and the like. The sanitary napkins are therefore sterilized in these hospitals before use and, as is usual in most hospitals wherein sterilizing equipment is continually in use and is always in demand, such napkin sterilization takes place not for a few napkins at a time, but for large packages containing very many napkins which are in direct, pressing contact with each other. As a matter of fact, in many cases the napkins are removed from the packages in which they are originally shipped by the manufacturer and packed into even larger, specially built containers so that the space within the sterilizer can be more efliciently utilized.

Unfortunately, such practice of either using the manufacturers pack-ages or the special containers has not worked out completely satisfactorily. In many cases, it has been found that adjacent napkins have become adhered to each other in such a way that the final, sterilized product is just one large block of napkins stuck to each other and which is separable into individual napkins only with difficulty and possible loss of the sterile nature of the napkins due to manual handling thereof.

The reasons for such sterilization difiiculties and blocking problems have been finally discovered and the solution thereof is now known. First, the previously-used adhesive binders, even though dried subsequently to their application to napkin covers, tend to return to their original tacky state at sterilization temperatures and thus cause the napkins to adhere to adjacent contacting napkins. Second, it has been established that previously-used adhesive binders, when initially applied to the napkin cover and while still in a fluid state tend to migrate to the intersections or crossings of the strands making up the gauze or scrim cover. This increased concentration of adhesive binder at the intersections therefore increases the potential adhesivity at such areas and thereby increases the blocking tendencies of the napkin cover. And, third, it has also been established that, when the sanitary napkins are pressed together during sterilization, that the pressure is increased at the strand intersections which, due to the strand-overlapping construction thereat, protrude slightly beyond the over-all plane of the napkin cover and receive the bulk of the pressure thereat rather than it being spread out evenly over the entire surface of the napkin. As a result, the contact pressure between adjacent napkins is localized at the areas of the strand intersections or crossings where it just so happens that the concentration of the binder adhesive is the greatest. The cumulative effect of these two latter factors, along with the nature of the binder, is considered the basic cause for blocking.

It has now been discovered that, if a non-migratory cellulosic binder is used as the adhesive and is applied to a gauze or scrim napkin cover containing interwoven or overlaid strands, such a binder does not tend to return to an adhesive form when exposed to elevated sterilizing temperatures. Additionally, such a cellulosic binder has a reduced tendency to migrate to the intersections of the fabricated napkin cover, whereby, when the sanitary napkins are pressed together subsequently during sterilization and such pressure is concentrated at the protruding intersections, any blocking tendency of the sanitary napkins is practically eliminated. And, finally, due to the inherent nature of such non-migratory cellulosic binders, it is possible to use considerably smaller amounts than those required by polyacrylic and polyvinyl resin binders without loss in bonding effectiveness whereby potential adhesivity is even further reduced.

Typical examples of such cellulosic binders used in the application of the present inventive concept are: regenerated cellulose and water-insoluble ethers of cellulose such as hydroxyethyl cellulose and carboxymethyl cellulose. It has been found that these cellulosic binders are essentially non-migratory in nature and show very little tendency to migrate to the strand intersections of the fabricated napkin cover.

The binder may be applied to the fabricated napkin cover by any desired method or apparatus known to the industry. Preferably, however, it is desired to apply the adhesive binder by passing the fabric cover in contact with an adhesive applicator roll partially immersed in a bath of the adhesive. Other methods may, of course, be used.

The amount of the adhesive to be applied may be varied within relatively wide limits depending upon the requirements and needs of the final product. Within the purposes of the present invention, it has been found that from about of 1% up to about 5% by weight has been found satisfactory, with preferred ranges extending from about 1% to about 3% by weight.

Such a low amount of required binder is considered another advantageous feature of the present invention in that normally about 2% by weight or less is satisfactory, whereas in the case of previously-used acrylic and vinyl resins, usually about 14% to about 17% by weight of binder is required.

After the adhesive binder agent is applied to the gauze or scrim napkin cover, it is occasionally desired to make the surface thereof softer by adding a light fibrous applique thereto. Such may be accomplished easily by applying such a fibrous applique while the adhesive binder is still fluid and tacky. In this way, the binder serves two purposes, namely, that of bonding the strands of the gauze or scrim and, secondly, that of securing the fibrous ap plique thereto.

In the accompanying drawings and following specification, there is illustrated and described preferred designs of sanitary napkin embodying the invention but it is to be understood that the invention is not to be considered limited to the constructions disclosed except as determined by the scope of the appended claims. With reference to the accompanying drawings,

FIGURE 1 is a perspective view, partially cut away, of one form of the improved sanitary napkin of the present invention;

FIGURE 2 is a cross-section of the sanitary napkin illustrated in FIGURE 1, taken on the line 2-2 thereof in the direction indicated by the arrows;

FIGURE 3 is an enlarged showing of that portion of the sanitary napkin encircled in FIGURE 2, showing the construction of the fabric cover in greater detail; and

FIGURE 4 is an enlarged showing of a portion of a sanitary napkin similar to the area cross-sectioned in FIGURE 2, but illustrating a modification of the fabric cover shown in FIGURES 1 through 3.

In the embodiments of the invention shown in the drawings, a sanitary napkin is shown in FIGURE 1, comprising a relatively thick, flexible, absorbent pad or core 12 of fluffed wood pulp fibers wrapped within a relatively thin pervious cover or sheath 14 folded about the core and overlapped at its extending ends 15 to provide pinning tabs for securing the sanitary napkin to a belt. The absorbent core 12 is shown merely as one large pad of fibrous absorbent material but such is merely illustrative and it is to be appreciated that any absorbent core of any desired construction may be used.

The relatively thin, pervious cover 14, illustrated in FIGURES 1 through 3, is scrim wherein the individual strands are merely laid across each other at an angle of 90 and in which one set of strands extends in the long direction of the napkin whereas the other set of strands extends across the width of the napkin. It is to be appreciated that the individual sets of strands need not necessarily be laid across each other at 90 but that they may be so laid at any other desired acute angle such as 30, 45, 60, etc. Additionally, it is to be noted that the strands need not extend directly along and directly across the napkin. If desired, the strands may be positioned at any other desired angle, such as each set of strands being at an angle of 30, 45 or 60 to the long direction of the napkin.

Reference to FIGURE 3 indicates that the strands 16 extending in the widthwise direction of the napkin are laid at an angle of about 90 across the individual strands 18 which extend in the long direction of the napkin. These strands 18, crossing the strands 16 as they do, consequently extend outwardly from the general plane of the scrim fabric and, if placed against a planar surface, for example, will contact this planar surface in pressure areas 20. In this way, any pressure exerted between the napkin 10 and the planar surface will be concentrated or localized at such pressure areas 20. It is thus realized that, if blocking takes place, it will most likely take place at such pressure areas 20.

In FIGURE 4 there is illustrated a modification of the sanitary napkin illustrated in FIGURES 1 through 3 in that a gauge fabric comprising cross strands (or wefts) 16' and long strands (or warps) 18' constitutes the napkin cover 14. Again, it is to be noted that certain portions of the cross strands 16 extend beyond the general plane of the gauze cover in a series of spaced pressure areas 20. Also, it is to be noted that, if the napkin were to be placed against a planar surface, the pressures would be concentrated or localized at the pressure areas 20 and that, if blocking takes place, it will most likely take place at pressure areas 20'.

The invention will be further illustrated in greater detail by the following specific examples. It should be understood, however, that although these examples may describe in particular detail some of the more specific features of the invention, they are given primarily for purposes of illustration and the invention in its broader aspects is not to be construed as limited thereto.

Example I A relatively thin, pervious 14 x 10 regular woven cotton gauze fabric is impregnated with about 14% by weight of polyalkylacrylate resin as the adhesive bonding agent. The bonded, stabilized gauze fabric is then wrapped around a relatively thick, flexible absorbent core of fluffed wood pulp fibers to form a sanitary napkin. This napkin is packed along with other similarly prepared napkins in a container with sufficient pressure so that all the napkins are in pressing contact with adjacent napkins. The container is then placed in a steam sterilizer and exposed to a sterilizing temperature of about 250 F. for about 25 minutes. The container of napkins is then removed from the sterilizer and cooled. Upon subsequent inspection, it is found that all the sterilized napkins are adhered into a solid inseparable block of napkins. The use of a regular woven gauze fabric as the napkin cover in combination with a polyalkylacrylate resin binder is not acceptable when sterilizability and anti-blocking is a requirement.

Example 11 A relatively thin, pervious 6 x 10 scrim fabric (nylon warp, viscose rayon filament filling) is impregnated with about 14% by weight of polyalkylacrylate resin as the adhesive bonding agent. The bonded, stabilized scrim fabric is then wrapped around a relatively thick, flexible absorbent core of flulfed wood pulp fibers to form a sanitary napkin. This napkin is packed along with other similarly prepared napkins in a container with sufiicient pressure so that all the napkins are in pressing contact with adjacent napkins. The container is then placed in a steam sterilizer and exposed to a sterilizing temperature of about 250 F. for about 25 minutes. The container of napkins is then removed from the sterilizer and cooled. Upon subsequent inspection, it is found that all the sterilized napkins are adhered into a solid inseparable block of napkins. The use of a scrim fabric as the napkin cover in combination with a polyalkylacrylate resin binder is not acceptable when sterilizability and anti-blocking is a requirement.

Example III A relatively thin, pervious 14x 10 regular woven cotton gauze fabric is impregnated with about 9% by weight of polyvinyl acetate resin as the adhesive bonding agent. The bonded, stabilized gauze fabric is then wrapped around a relatively thick, flexible absorbent core of flutfed wood pulp fibers to form a sanitary napkin. This napkin is packed along with other similarly prepared napkins in a container with suflicient pressure so that all the napkins are in pressing contact with adjacent napkins. The container is then placed in a steam sterilizer and exposed to a sterilizing temperature of about 240 F. for about 30 minutes. The container of napkins is then removed from the sterilizer and cooled. Upon subsequent inspection, it is found that all the sterilized napkins are adhered into a solid inseparable block of napkins. The use of a regular woven gauze fabric as the napkin cover in combination with a polyvinyl acetate resin binder is not acceptable when sterilizability and anti-blocking is a requirement.

Example IV A relatively thin, pervious 6 x 10 scrim fabric (nylon Warp, viscose rayon filament filling) is impregnated with about 14% by weight of polyvinyl chloride resin as the adhesive bonding agent. The bonded, stabilized scrim fabric is then Wrapped around a relatively thick, flexible absorbent core of fluifed wood pulp fibers to form a sanitary napkin. This napkin is packed along with other similarly prepared napkins in a container with sufiicient pressure so that all the napkins are in pressing contact with adjacent napkins. The container is then placed in a steam sterilizer and exposed to a sterilizing temperature of about 260 F. for about 20 minutes. The container of napkins is then removed from the sterilizer and cooled. Upon subsequent inspection, it is found that all the sterilized napkins are adhered into a solid inseparable block of napkins. The use of a regular woven gauze fabric as the napkin cover in combination with a polyvinyl chloride resin binder is not acceptable when sterilizability and antiblocking is a requirement.

Example V A relatively thin, pervious 14 x regular Woven gauze fabric is impregnated with about l /z% by weight of regenerated cellulose (viscose process) as the adhesive bonding agent. The bonded, stabilized gauze fabric is then Wrapped around a relatively thick, flexible absorbent core of fluffed Wood pulp fibers to form a sanitary napkin. This napkin is packed along with other similarly prepared napkins in a container with sufiicient pressure so that all the napkins are in pressing contact with adjacent napkins. The container is then placed in a steam sterilizer and exposed to a sterilizing temperature of about 250 F. for about 25 minutes. The container of napkins is then removed from the sterilizer and cooled. Upon subsequent inspection, it is found that the sterilized napkins have not blocked and are still individually separable. The use of a regular woven gauze fabric as the napkin cover in combination with a regenerated cellulose binder is acceptable when sterilizability and anti-blocking is a requirement.

Example VI A relatively thin, pervious 6 x 10 scrim fabric (nylon warp, viscose rayon filament filling) is impregnated with about 2% by weight of regenerated cellulose (viscose process) as the adhesive bonding agent. The bonded, stabilized scrim fabric is then Wrapped around a relatively thick, flexible absorbent core of fiuifed wood pulp fibers to form a sanitary napkin. This napkin is packed along with other similarly prepared napkins in a container with sufiicient pressure so that all the napkins are in pressing contact with adjacent napkins. The container is then laced in a steam sterilizer and exposed to a sterilizing temperature of about 235 -F. for about 30 minutes. The container of napkins is then removed from the sterilizer and cooled. Upon subsequent inspection, it is found that the sterilized napkins have not blocked and are still individually separable. The use of a scrim fabric as the napkin cover in combination with a regenerated cellulose binder is acceptable when sterilizability and anti-blocking is a requirement.

Example VII A relatively thin, pervious 14 x 10 regular woven gauze fabric is impregnated with about 2% by weight of hydroxyethyl cellulose as the adhesive bonding agent. The bonded, stabilized gauze fabric is then wrapped around a relatively thick, flexible absorbent core of flutfed wood pulp fibers to form a sanitary napkin. This napkin is packed along with other similarly prepared napkins in a container with sufiicient pressure so that all the napkins are in pressing contact with adjacent napkins. The container is then placed in a steam sterilizer and exposed to a sterilizing temperature of about 265 F. for about minutes. The container of napkins is then removed from the sterilizer and cooled. Upon subsequent inspection, it is found that the sterilized napkins have not blocked and are still individually separable. The use of a regular woven gauze fabric as the napkin cover in combination with a hydroxyethyl cellulose binder is acceptable when sterilizability and anti-blocking is a requirement.

Example VIII A relatively thin, pervious 6 x10 scrim fabric (nylon warp, viscose rayon filament filling) is impregnated with about 2% by weight of hydroxyethyl cellulose as the adhesive bonding agent. The bonded, stabilized scrim fabric is then wrapped around a relatively thick, flexible absorbent core of fluffed wood pulp fibers to form a sanitary napkin. This napkin is packed along with other similarly prepared napkins in a container with sufficient pressure so that all the napkins are in pressing contact with adjacent napkins. The container is then placed in a steam sterilizer and exposed to a sterilizing temperature of about 250 F. for about 25 minutes. The container of napkins is then removed from the sterilizer and cooled. Upon subsequent inspection, it is found that the sterilized napkins have not blocked and are still individually separable. The use of a scrim fabric as the napkin cover in combination with a hydroxyethyl cellulose binder is acceptable when sterilizability and anti-blocking is a requirement.

Although several specific examples of the inventive concept have been described, the same should not be construed as limited thereby nor to the specific features mentioned therein but to include various other equivalent features as set forth in the claims appended hereto. It is understood that any suitable changes, modifications and variations may be made without departing from the spirit and scope of the invention.

What is claimed is:

1. A sanitary napkin capable of being sterilized with out blocking comprising, in combination, a relatively thick, flexible, absorbent core and a relatively thin, pervious fabricated cover wrapped around said core, said pervious fabricated cover comprising textile strands crossing each other at intersections which extend outside the general plane of the fabricated cover, said strands being bonded to each other by a non-migratory cellulosic binder whereby the sanitary napkin is capable of being sterilized at temperatures of from about 225 F. to about 275 F. in pressing contact with adjacent sanitary napkins without adhering thereto and blocking.

2. A sanitary napkin capable of being sterilized without blocking comprising, in combination, a relatively thick, flexible, absorbent core and a relatively thin, pervious fabricated cover wrapped around said core, said pervious fabricated cover comprising textile strands crossing each other at intersections which extend outside the general plane of the fabricated cover, said strands being bonded to each other by a non-migratory regenerated cellulose binder whereby the sanitary napkin is capable of being sterilized at temperatures of from about 225 F. to about 275 F. in pressing contact with adjacent sanitary napkins without adhering thereto and blocking.

3. A sanitary napkin capable of being sterilized without blocking comprising, in combination, a relatively thick, flexible, absorbent core and a relatively thin, pervious fabricated cover wrapped around said core, said pervious fabricated cover comprising textile strands crossing each other at intersections which extend outside the general plane of the fabricated cover, said strands being bonded to each other by a non-migratory hydroxyethyl cellulose binder whereby the sanitary napkin is capable of being sterilized at temperatures of from about 225 F. to about 275 F. in pressing contact with adjacent sanitary napkings without adhering thereto and blocking.

4. A sanitary napkin capable of being sterilized without blocking comprising, in combination, a relatively thick, flexible, absorbent core and a relatively thin, pervious fabricated cover wrapped around said core, said pervious fabricated cover comprising gauze containing textile strands crossing each other at intersections which extend outside the general plane of the fabricated cover, said strands being bonded to each other by a non-migratory cellulosic binder whereby the sanitary napkin is capable of being sterilized at temperatures of from about 225 F. to about 275 F. in pressing contact with adjacent sanitary napkins without adhering thereto and block- 1n 5. A sanitary napkin capable of being sterilized without blocking comprising, in combination, a relatively thick, flexible, absorbent core and a relatively thin, pervious fabricated cover wrapped around said core, said pervious fabricated cover comprising scrim containing textile strands crossing each other at intersections which extend outside the general plane of the fabricated cover, said strands being bonded to each other by a non-migratory cellulosic binder whereby the sanitary napkin is capable of being sterilized at temperatures of from about 225 F. to about 275 F in pressing contact with adjacent 5 sanitary napkins without adhering thereto and blocking.

References Cited in the file of this patent UNITED STATES PATENTS 2,486,805 Seymour et a1 Nov. 1, 1949 2,702,780 Lerner Feb. 22, 1955 2,833,283 Spahr et a1. May 6, 1958 10 2,900,980 Harwood Aug. 25, 1959 2,902,037 Harwood et a1 Sept. 1, 1959 FOREIGN PATENTS 156,756 Australia May 27, 1954 

1. A SANITARY NAPKIN CAPABLE OF BEING STERILIZED WITHOUT"BLOCKING" COMPRISING, IN COMBINATION, A RELATIVELY THICK, FLEXIBLE, ABSORBENT CORE AND A RELATIVELY THIN, PERVIOUS FABRICATED COVER WRAPPED AROUND SAID CORE, SAID PERVIOUS FABRICATED COVER COMPRISING TEXTILE STRANDS CROSS- 